The present invention relates to a process for manufacturing disposable diapers and briefs having cut-outs for the leg openings which are curvilinear in shape and are provided over at least a part of their inner periphery with elastic elements improving leak-tightness around the leg openings.
Another object of the invention is also to provide the disposable diapers and briefs obtained by application of the process of the invention. These diapers or diaper briefs can be discarded after use and can be used for infants or for incontinent adults. They consist of an impermeable outer backing sheet, an absorbent pad forming an integral part of the assembly and preferably of a permeable facing web acting as the inner diaper liner.
In order to improve the seal around the leg openings of disposable diapers of this type it has already been suggested that rectilinear elastic strips be adhered in the stretched state onto an impermeable sheet designed to form the outer envelope of the diaper unit.
As an example of products of this type, mention may be made of the disposable diapers described in U.S. Pat. Nos. 3,860,003 and 4,050,462. The elastic elements placed near to the margin of the leg openings in such diapers in order to improve the leaktightness at this spot must not, however, grip too tightly or lead to folds being formed in the material, and notably in the material forming the absorbent pad, in order to respect the user's anatomy whether this is an adult or an infant.
In order to improve the profile of diapers fitted with such crotch elastics, a special absorbent pad structure has already been designed, as described in French patent application No. 2,438,434.
The operation of making curvilinear shaped openings or crotch cut-outs has so far meant that it was not possible to manufacture, continuously on an industrial scale and at a high rate, this type of diaper having elastics round the edge, owing to the curved shape of the periphery.
Disposable diapers of this type having an elastic tape on the edge of the curvilinear leg opening as described in French Pat. No. 2,063,794 can only be made by methods which are not very suitable for high-output manufacture, notably by sewing elastic tapes or threads.